[백준] 19939 박 터뜨리기 - Greedy / Java

• 문제 링크

19939번: 박 터뜨리기

 

• 풀이 과정

 

• 풀이 코드

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.util.StringTokenizer;

public class Main {

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
        StringTokenizer st = new StringTokenizer(br.readLine());

        int n = Integer.parseInt(st.nextToken());
        int k = Integer.parseInt(st.nextToken());

        n -= k * (k + 1) / 2;

        int cnt = n < 0 ? -1 : n % k == 0 ? k - 1 : k;

        bw.write(String.valueOf(cnt));
        bw.flush();
    }

}